Unraveling the molecular mechanisms underlying flat stem formation in Atractylodes lancea in response to phytoplasmas.

For centuries, the herb Atractylodes lancea (Thunb.) has been revered for its pharmacological properties, particularly its efficacy in combating spleen and stomach ailments. However, prolonged artificial cultivation of A. lancea has led to an increased presence of serious plant diseases, including flat branch disease caused by phytoplasmas. To elucidate the mechanisms of flat stem (FS) formation, physiological and biochemical indicators, as well as related metabolic pathways were assessed in A. lancea stems following phytoplasma infection. The results demonstrated significant changes in the levels of stress compounds H₂O₂ and MDA, as well as the activities of antioxidant enzymes APX, POD, PPO, and CAT. Additionally, the FS structures of A. lancea exhibited elevated levels of JA and zeatin, accompanied by a decrease in auxin content. High-throughput sequencing identified differentially expressed genes (DEGs) enriched in various pathways, including hormone biosynthesis, signal transduction, and Ca²⁺ signalling. These findings enhance our understanding of phytoplasma-induced FS development in A. lancea and provide a basis for future molecular studies.